Many physiological changes are experienced as women go through menopause. It is believed that a significant majority, perhaps as high as 80 percent, of women experience the discomfort of the “hot flash/flush” associated with menopause. A hot flash is believed to be the result of the hormonal changes, particularly the decline in estrogen levels that occurs during menopause. Although some sources differentiate between a “hot flash” and “hot flush,” both conditions will be referred to herein collectively as “hot flash” or “hot flashes.” A hot flash is marked by an increase in body temperature accompanied by an intense feeling of unbearable heat, particularly internally radiating body heat. A hot flash may also be accompanied by an increase in heart rate, dizziness, anxiety, faintness, a sense of unease, tingling sensations, pressure in the head, nausea, perspiration, and feelings of breathlessness. The feeling of heat is often concentrated in the area of the face and neck, and sometimes spreads to the area of the upper chest. Although a hot flash may last for as short as a minute, a hot flash usually lasts as long as two to three minutes, and may last as long as an hour. Regardless of the duration of the hot flash, the discomfort due to the intense feeling of heat is extremely uncomfortable and disconcerting to a woman experiencing the hot flash.
When a woman experiences a hot flash, the first detectable change is an increase in finger blood flow with a concomitant enhancement of skin conductance, as well as a change in temperature of the skin of the face and neck. The increase in skin conductance is followed rapidly by a sharp rise (1-7° C.) in finger temperature. The degree to which finger temperature rises during a hot flash is inversely proportional to the base-line finger temperature before the flash. Thus, a 0.50° C. increase in finger temperature in a woman with a base-line finger temperature of 35° C. may be as good a measure of the occurrence of a hot flash as a 5° C. increase in finger temperature in a woman with base-line finger temperature of 29° C., because of the non-linear relationship between skin temperature and blood flow. As vasodilation and sweating ensue, internal body temperature drops. The magnitude of decrease in core temperature ranges from 0.10° C. to 0.90° C. The onset of sweating is rapid and is particularly profuse in the face and scalp. It may occur in five minute bursts accompanying short, discrete hot flashes, or continue in waves for more than thirty minutes during prolonged hot flashes. A hot flash is the inverse of a fever. In mammals, the control of body temperature resembles a negative feedback system in which a set point temperature serves as reference for the thermoregulatory mechanism. A fever can be understood as the upward adjustment of this temperature set point. In a febrile episode, the set point is first elevated, initiating vasoconstriction, shivering and behavioral modifications, such as the addition of blankets. This results in an elevation of body temperature to a level that is maintained for a period of time. A hot flash, on the other hand, is a transient downward adjustment of the set point, which results in the sensation of heat. At the end of a hot flash, the set point returns to normal. The trigger for a change in set point may be a series of nerve impulses. A fever, even with a rapid onset, may last for hours, days or even weeks. In contrast, the duration of a hot flash is in the order of minutes.
A number of products, systems and methods are known for eliminating hot flashes and/or for alleviating the effects of hot flashes. Some of the known approaches involve application of a composition to the skin. Often, the compositions include ingredients that are not miscible with each other and, therefore, the compositions are multi-phase. With more than one phase, there is always the possibility of destabilization and separation. Additionally, the known compositions are often delivered via a pressurized (i.e. aerosol) dispensing container. Aerosol packaging may have one or more disadvantages including higher cost, environmental concerns and inhalation concerns. Further, because of the mode of dispensing, there may be limitations on the ingredients that can be dispensed from aerosol packaging. In providing a product to alleviate the symptoms of hot flashes, the vehicle by which the product is delivered to the user should be harmonious with the initial signs and spread of hot flash symptoms. Hot flashes are most commonly associated with the discomforting symptom of an intense feeling of heat that begins in the face, neck, or chest regions and then radiates to other parts of the body. However, prior to the intense feeling of heat, many women experience a premonition of an impending hot flash that is accompanied by symptoms, such as a feeling of unease or anxiety, a feeling of pressure in the head, or tingling sensations. During this time, there is a concurrent increase in heart rate, digital blood flow, and vasodilation of blood vessels of the skin. At this point, women will experience an intense feeling of heat which may further be accompanied by feelings of dizziness, nausea and breathlessness. For most women who experience hot flashes, these foregoing symptoms are very unpleasant. Indeed, for some women the extent of these symptoms experienced during a hot flash can be downright unbearable. In order to respond to and alleviate the discomfort associated with the initial symptom of the intense feeling of heat that begins in the face, neck and/or chest, it would be desirable to provide a composition that lends itself to convenient topical application to the skin of these body areas.
Known compositions that are formulated to alleviate the discomfort associated with hot flashes often include volatiles like ethanol to provide immediate cooling, but the relief provided by such compositions dissipates quickly. The period of relief may be extended by also including a neurosensory agent, such as menthol. However, the scent associated with the neurosensory agent may not be pleasant and a neurosensory agent such as menthol may begin to irritate the skin of the user if used for a prolonged period. Another approach taken in known compositions is to use a phase change material to provide a cooling effect, but as with volatiles, the soothing effect may not last very long. Further, these traditional “cooling agents” do not address the sweating that occurs with hot flashes. In order to address the sweating, an antiperspirant salt may be added to the composition. However, the antiperspirant salts are generally used at a relatively high level to stop the sweating which may cause skin irritation—particularly when the composition is being applied over a larger skin surface area.
While compositions for alleviating the symptoms of hot flashes are known, there remains a need in the art for a temperature management composition that provides a cooling effect and prevents sweating for a period of greater than one minute. Additionally, there remains a need for a temperature management composition that is single phase and does not need to be applied using aerosol packaging. Further, there remains a need for a temperature management composition that is not irritating to the skin with regular use and that can be used on a relatively large area of the skin surface of the user.